posted 08-09-2011 03:29 PM
Would the first launch attempt of STS-93 be considered a launch pad abort or simply a scrub? There was a manual cutoff split seconds before the start of main engines, but after the igniters — the sparkler thingies — lit.

If it's not an abort, what's the textbook definition?

BenMember

Posts: 1843From: Daytona Beach, FLRegistered: May 2000

posted 08-09-2011 03:54 PM
A Redundant Set Launch Sequencer (RSLS) abort does not have to mean after the engines ignite. STS-93 was indeed an RSLS abort, and you can hear Leinbach discuss it with the team here (first asking and then getting confirmation) at 1:45 in.

STS-56 also had an RSLS abort around T-11 seconds.

RickMember

Posts: 264From: Yadkinville, NCRegistered: Jun 2000

posted 08-11-2011 07:47 PM
I received an e-mail from Eileen Collins this afternoon, and she had checked with the booster flight controller for STS-93 and copied me on his reply. According to him, the early shutdown was NOT considered a pad abort because the SSMEs did not start. Also, he continued, it was not an RSLS abort since it was a manual ground launch sequencer cutoff. Therefore, it evidently must be considered a scrub.

I'm just sayin' ...

Jay ChladekMember

Posts: 2211From: Bellevue, NE, USARegistered: Aug 2007

posted 08-12-2011 03:50 AM
And if it was an abort, they would have spent a longer period of time turning it around before a launch. As I recall, it was a 24 hour turnaround before launching the next night.

BenMember

Posts: 1843From: Daytona Beach, FLRegistered: May 2000

posted 08-12-2011 10:02 PM
No, the abort occurred July 20, and it was an automatic 48 hour scrub. It was then scrubbed a second time due to lightning, launching three days after the first attempt on July 23.

pslossMember

Posts: 17From: Registered: Jun 2011

posted 08-18-2011 08:17 PM

quote:Originally posted by Ben:STS-93 was indeed an RSLS abort, and you can hear Leinbach discuss it with the team here (first asking and then getting confirmation) at 1:45 in.

Actually, you can hear the GLS console operator say this was a RSLS hold, not an abort. The difference is when cutoff is given -- before the first engine start command, it's a RSLS hold; after, it's a RSLS abort.

Ken HavekotteMember

Posts: 1823From: Merritt Island, Florida, BrevardRegistered: Mar 2001

posted 08-18-2011 10:38 PM
While STS-93 in July 1999 was not a RSLS abort, there were five times it did occur.

First with Discovery's maiden launch on Mission 41-D, Challenger on 51-F, Discovery again on STS-51, Columbia/STS-55, and with a first launch attempt halted at T-1.9 seconds with Endeavour on STS-68 on Aug. 18, 1994.

Only Atlantis was spared from a pad abort like this in the shuttle program history.

Heck, I was there and covered all these missions first-hand here at Kennedy.

SpaceAholicMember

Posts: 3023From: Sierra Vista, ArizonaRegistered: Nov 1999

posted 02-27-2012 12:09 PM
During the "successful" launch of STS-93, a near catastrophic event occurred in one of the shuttle's SSME's. In a practice which in retrospect is surprising and symptomatic of the culture which precipitated STS-107, SSME's with faulty injector components (Liquid Oxygen (LOX) Posts) were routinely plugged up with pins and disabled (effectively deactivating a portion of the engine's injector) rather then removing and replacing the post. As briefed within this NASA Ames presentation, one of the pins was ejected during flight and resulted in additional engine damage.

posted 02-29-2012 12:54 PM
And keep in mind that the "sparkies" are not from SSME ignitor systems but rather "hydrogen burn-off igniters", meant to burn spilled hydrogen from the vicinity of the engines, as previously discussed here.